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Publication numberUS5695612 A
Publication typeGrant
Application numberUS 08/732,072
Publication dateDec 9, 1997
Filing dateOct 16, 1996
Priority dateJun 3, 1994
Fee statusLapsed
Also published asCA2168754A1, CA2168754C, DE69523258D1, DE69523258T2, EP0712455A1, EP0712455B1, US5620566, WO1995033885A1
Publication number08732072, 732072, US 5695612 A, US 5695612A, US-A-5695612, US5695612 A, US5695612A
InventorsKari Holopainen
Original AssigneeValmet Corporation
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pressing load shoe which is in direct engagement with water permeable wire supporting paper web against suction roll by fluid pressure, using fluid as lubricant
US 5695612 A
Abstract
A prepress for a paper web in a paper machine including a load shoe which is pressed against a backing element, preferably a vacuum roll, by a load pressure generating by a medium, preferably liquid, which at the same time acts as a lubrication medium in the prepress. The load shoe is in direct engagement with a water permeable wire upon which the paper web is supported.
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Claims(7)
I claim:
1. A method for pressing a paper web, comprising the steps of:
supporting the web in direct engagement with a water-permeable first wire,
arranging a load shoe in a loop of the first wire such that a front surface of said load shoe is in direct engagement with the first wire,
arranging a suction roll in opposed relationship to said load shoe such that the first wire passes between said suction roll and said load shoe,
pressing said load shoe toward said suction roll by means of pressure provided by a fluid medium,
lubricating said front surface of said load shoe by directing the fluid medium thereto, and
applying negative pressure through a suction zone of said suction roll such that the fluid medium is drawn into said suction roll through the first wire and the web and water from the web is drawn into said suction roll.
2. The method of claim 1, further comprises the steps of:
supporting the web in direct engagement with a water-permeable second wire, and
passing the second wire between the web and said suction roll, whereby the fluid medium is drawn into said suction roll through the first wire, the web and the second wire and water from the web is drawn into said suction roll through the second wire.
3. The method of claim 1, further comprising the steps of:
arranging said suction roll in nip-defining relationship with said load shoe, and
pressing said load shoe against said suction roll to intensify the dewatering of the web.
4. The method of claim 1, further comprising the steps of:
arranging said load shoe and said suction roll at a location between a forming section and a press section of a paper machine,
supporting the web in direct engagement with a water-permeable second wire,
arranging said suction roll in nip-defining relationship with said load shoe, and
passing the web supported by and between the first and second wires between said load shoe and said suction roll.
5. A press for pressing a paper web as the web is supported in direct engagement with a water-permeable first wire, comprising
a load shoe arranged in a loop of the first wire, said load shoe having a front surface in direct engagement with the first wire,
a backing element situated in opposed relationship to a front surface of said load shoe such that the first wires passes between said backing element and said load shoe,
first means for directing a fluid pressure medium to press said load shoe toward said backing element,
second means for directing said pressure medium onto said front surface of said load shoe to lubricate said front surface of said load shoe, and
wherein said backing element is a suction roll having a suction zone opening toward said front surface of the load shoe, a suction force being applied through said suction zone in said suction roll to draw said pressure medium and water removed from the web into said suction zone.
6. The press of claim 5, wherein said pressure medium is water or an aqueous mixture.
7. The press of claim 5, wherein the press is situated between a forming section and a press section of a paper machine, the web being in direct engagement with a second wire such that the web is supported by and between said first and second wires between said load shoe and said suction roll.
Description

This is a continuation of U.S. patent application Ser. No. 08/459,111 filed Jun. 2, 1995 now U.S. Pat. No. 5,620,566.

BACKGROUND OF THE INVENTION

The present invention relates to a prepress for paper web in which a web is carried between two wires and pressed to remove water therefrom. The present invention also relates to a method for lubricating a load shoe in a prepress and pressing the load shoe against a backing element situated in opposed relationship to the load shoe.

In the prior art, so-called prepress equipment is known in paper drying in which a separate load shoe is situated within a flexible, closed (oil-impermeable) glide-belt mantle and is used to press the web running between wires, preferably in conjunction with a vacuum roll. The vacuum roll is a roll provided with a vacuum box in its interior whereby with the aid of a vacuum produced therein, water is drawn off from the web through perforations in the roll shell, and preferably also through separate circumferential grooving. A particular drawback in conventional prepress arrangements has been finding an appropriate operating system for the load shoe. Use of oil as the operating liquid in the operating system of the load shoe necessitates that the arrangement be well housed in order to prevent leakages of oil.

It is a problem in conventional prepress arrangements utilizing oil as the operating liquid that there is the potential for the oil to leak and contaminate lubricating medium applied to lubricate the load shoe of the prepress arrangement vis-a-vis the wire passing thereover and thus the web.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the invention to provide a new and improved prepress arrangement in which the problem of leakage of an operating fluid contaminating the lubricating medium is eliminated.

It is another object of the invention to provide a new and improved method in a prepress arrangement in which a single fluid is used to both lubricate the load shoe and press the load shoe against a backing element situated in opposed relationship thereto.

In order to achieve these objects, and others, the present invention is directed to a novel type of load shoe of a prepress for paper web. In the invention, as the operating liquid of the load shoe, the same liquid used for lubrication of the shoe is used, i.e., there is only a single medium or liquid which is used both for lubrication and as the operating fluid of the load shoe. Preferably, the fluid used in the invention is water so that not only is the operating fluid and the lubricating fluid the same, but also it is the very same liquid which is being removed from the web. Therefore, the system can be open and there is no need to house and shelter it from the elements. Any spilled water is gathered in a gathering trough situated adjacent the shoe and is conducted back into circulation.

In the prepress in accordance with the invention, in the wire section the water removal is intensified by pressing the load shoe against the vacuum roll. The web is conducted between the press shoe and the vacuum roll preferably between two wires or felts, which herein are generally referred to as weaves. For the load liquid of the shoe press, water is used in a preferred embodiment of the invention. In this case the water serves thus both as lubrication medium and as a medium producing simultaneous load pressure, i.e., the pressure medium. With the aid of water, the shoe is pressed against the back roll, the degree of pressing corresponding to the amount of pressure provided by the flow of water. The wire on the side of the shoe may be water-permeable, slightly water-permeable or water-impermeable.

In one embodiment of the invention, the water or other fluid is pumped from a container along pipes at load pressure into one or more loading chambers, whereby the pressure of the water exerts an effect on the load shoe, pressing it against a backing surface of the load shoe. The water acts at the same time as lubrication medium. From the pressure volume in conjunction with the load shoe, a passage is provided to the front surface of the load shoe and preferably to a groove on the front edge of the load shoe relative to the propagation direction of the web. The groove extends across substantially the entire width of the load shoe. As such, the lubrication medium, preferably water, is conducted to the front edge of the load shoe and a mobile felt transfers the lubrication medium in the form of a film to the surface of the load shoe. On the other side of the load shoe, the trailing side, the lubrication medium is gathered into a trough and conducted further back into water circulation.

In the method in accordance with the invention, a front surface of the load shoe in arranged in opposed relationship to the backing element, the load shoe is pressed against the backing element by means of pressure provided by a fluid medium, and the front surface of the load shoe is lubricated by directing the medium thereto. Thus, a single medium serves to load the load shoe and lubricate the front surface of the same. Further, a pair of wires carrying a web therebetween is directed into a nip defined between the load shoe and the backing element whereby the front surface of the load shoe engages with one of the wires. If the medium is water, the water removed in the nip from the wires and the web may be collected after the wires and web have passed through the nip, and recirculated to press the load shoe and lubricate the front surface thereof.

The invention is described below referring to certain preferred embodiments presented in the figures of the accompanying drawings. However, the invention is not intended to be exclusively restricted to the illustrated embodiments alone.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of embodiments of the invention and are not meant to limit the scope of the invention as encompassed by the claims.

FIG. 1 shows a cross-sectional view of prepress in accordance with the invention.

FIG. 2 shows the lubrication medium/load medium circulation arrangement of the prepress shown in FIG. 1 in the machine direction wherein the collector tank is shown in a position below the vacuum roll for illustration purposes only.

FIG. 3 shows the prepress in accordance with the invention in a more comprehensive context.

FIG. 4A shows a longitudinal, cross-sectional view of an embodiment of the invention taken along the line 4--4 in FIG. 1.

FIG. 4B shows a longitudinal, cross-sectional view of another embodiment of the invention taken along the line 4--4 in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings wherein like reference numerals refer to the same or similar element, in the prepress shown in FIG. 1, a prepress nip N1 is formed between a load shoe 10 and a back-up roll, preferably a vacuum roll 11. Wires/weaves H1 and H2 carry a web W therebetween and are conducted via nip N1 from the left side in FIG. 1. Water removal occurs in nip N1 into an internal vacuum space 0 in the vacuum roll 11 defined by chamber means. The vacuum or suction effect is intensified by pressing the load shoe 10 against an outer surface 11'a of a shell 11a of the vacuum roll 11. The load shoe has an outer or front surface 10' which substantially corresponds to the shape of the roll shell 11a. The load shoe 10 is movably connected to a seat 13. The load shoe 10 comprises web plate part 10a and branch parts 10b1, 10b2 extending therefrom. The seat 13 comprises a web plate part 13a and branch parts 13b1, 13b2, and at ends of the branch parts, inwardly directed edges 13d1, 13d2. In the approximate center point of the web plate part 13a, a neck part 13c is attached so that spaces E1 and E2 are defined between the neck 13c and the side walls 13b1, 13b2. The side branches 10b1, 10b2 of load shoe 10 are disposed in a respective one of the spaces E1, E2.

A medium, preferably water, is conducted by pressure via channel 15 in neck 13c into a space defined between the neck 13c of the seat 13 and the load shoe 10 which is chamber D. The medium is passed or flows from the space D onward via a channel 16 in web plate part 10a into a groove 17 on the front surface 10' of the load shoe. The medium is liquid, preferably water or an aqueous mixture. The groove 17 is arranged to extend over substantially the entire length of the load shoe. Also, the medium may be passed to a longitudinally extending groove 17b in the front surface of the web plate part 10a through a channel 16b in a center region of the web plate part 10a to thereby lubricate a larger portion of the front surface of the web plate part 10a.

In space D, the pressure of the medium generates a force on the undersurface (rear surface) of the web plate part 10a of the load shoe 10, thereby pressing the load shoe 10 against its abutting surface, preferably against the outer surface 11a' of the shell 11a of the vacuum roll 11. The branch parts 10b1, 10b2 move in the spaces E1, E2, respectively, during movement of the web plate part 10a of the load shoe 10. Web W and the wires/weaves H1 and H2 pass via the surfaces, i.e., via the nip N1 between the front surface 10' of the load shoe 10 and the outer surface 11'a of the shell 11a of the vacuum roll 11.

The medium, which is preferably water, is conducted via branch channels C1, C2, . . . of a manifold J arranged within a frame beam P and mounted thereto into channel 15 to be conducted into space D. Any spilled water and water leaving the load shoe are conducted into a trough 20 arranged after the frame beam P in a running direction of the wires/weaves and web and then back into water circulation.

The prepress shown in FIG. 1 comprises a vacuum roll 11 as a backing element. However, it is possible that another roll may be used instead of vacuum roll 11, such as a roll provided with a recessed surface.

FIG. 2 shows a liquid circulation arrangement of a prepress in accordance with the invention. The medium is conducted via the branch channels C1, C2, . . . of the manifold J within the frame beam P to one or more chambers D between the rear surface of the load shoe 10 and the seat 13, and the load shoe 10 is pressed in line with the surfaces of the branch parts 13b1, 13b2 of the seat 13 towards the backing element 11, e.g., especially toward the vacuum roll 11. Any water discharged from the load shoe 10 with wire/weave H2 is conducted into a collector tank 20 situated below the vacuum roll 11, from there along a channel 21 into a liquid container 22 and furthermore, is then pumped through a pump 23 along channel 24 back into the manifold J to be recirculated through the load shoe 10.

FIG. 3 shows an application of the prepress in accordance with the invention. Traveling of the web W is represented by arrows L1 and the circulation directions of felt transfers with arrows L2 and L3. Web W is conducted from a felt circulation wire/weave H3, at the point of separation after the forming section, and is transferred in line with wire/weave H1 between wire/weave H1 and wire/weave H2, and into nip N1. The water is gathered in trough 20 and moved back into manifold J. Thereafter, the web is carried on wire/weave H1 to be transferred therefrom and carried further by additional wire, weaves or felts into the press section of the paper machine. Thus, in this embodiment, the prepress is arranged between the forming section and the press section of the paper machine.

In the embodiment shown in FIGS. 4A and 4B are sectional view of different embodiments taken through the line 4--4 of FIG. 1. In these embodiments, there are a plurality of chambers D1, D2, D3, . . . between the neck portion 13c and the web plate part 10a. A dedicated channel h leads to each of the chambers D1, D2, D3, . . . As shown in FIG. 4A, the neck portion 13c has projections g2 and the rear surface of the web plate part 10a also has projections gl. Between projections g1 and g2, sealing structures e1, e2 are provided to seal the chambers. As shown in FIG. 4B, the neck portion 13c has projections g1 and recesses t2 and the rear surface of the web plate part 10a also has projections g2 and recesses t1. Between projections g1 and g2, sealing structures e1, e2 are provided to seal the chambers. In this manner, by directing variable amounts of the pressure medium to the chambers, e.g., by appropriate regulation of the flow of the medium from the manifold J, it is possible to adjust the loading pressure provided by the load shoe along the width of the shoe, e.g., to profile the moisture content of the paper web at different positions of width. Also, in these embodiments, the web plate part 10a of the load shoe 10 may be made of a flexible material such as plastic.

The examples provided above are not meant to be exclusive. Many other variations of the present invention would be obvious to those skilled in the art, and are contemplated to be within the scope of the appended claims.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3853698 *Apr 17, 1972Dec 10, 1974Beloit CorpLarge roll hydraulic press with pressurized fluid supports
US4556454 *Jan 28, 1985Dec 3, 1985Sulzer-Escher Wyss GmbhWet press for dewatering a web of material
US4568423 *Oct 13, 1983Feb 4, 1986Valmet OyPaper or cardboard webs
US4570314 *Jun 4, 1982Feb 18, 1986Escher Wyss AktiengesellschaftPress roll
US4917768 *May 2, 1989Apr 17, 1990Valmet Paper Machinery, Inc.Press with extended nip
US4923570 *Mar 2, 1989May 8, 1990J. M. Voith GmbhLong nip press roll arrangement
US4976820 *Apr 28, 1988Dec 11, 1990Valmet Paper Machinery Inc.Low pressure dewatering between heated cylinders for longer times; papermaking
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6221214Dec 22, 1997Apr 24, 2001Voith Sulzer Papiermaschinen GmbhWet press and method for treating a fibrous material web
US6235158 *Dec 17, 1997May 22, 2001Voith Sulzer Papiermaschinen GmbhSuction forming roll n double screen method and machine for the manufacture of a fibrous material web
US6685610 *May 4, 2001Feb 3, 2004Metso Paper, Inc.Deflection compensated roll for paper/board or finishing machine
US7510630Apr 20, 2005Mar 31, 2009Albany International Corp.concavely-shaped pressure surface of shoe increases amount of wrap that a making fabric has on a cylinder mould or sieve thereby increasing friction generated between the making fabric and the cylinder mould or sieve; results in an improved torque transfer between the making fabric and the cylinder mould
Classifications
U.S. Classification162/205, 162/358.3, 162/305, 162/217
International ClassificationD21F3/02
Cooperative ClassificationD21F3/0218
European ClassificationD21F3/02B2
Legal Events
DateCodeEventDescription
Feb 7, 2006FPExpired due to failure to pay maintenance fee
Effective date: 20051209
Dec 9, 2005LAPSLapse for failure to pay maintenance fees
Jun 29, 2005REMIMaintenance fee reminder mailed
Jun 5, 2001FPAYFee payment
Year of fee payment: 4